Q. Jesus said that “anyone who looks at a woman lustfully has already committed adultery with her in his heart.” But what if neither one is married? How could that be adultery? And I don’t think many married couples would be together if there weren’t some lust involved.
The saying of Jesus that you’re asking about comes from the part of the Sermon on the Mount where he’s showing that legalistic interpretations of the law of Moses are contrary to its true spirit and intentions. The Pharisees taught that so long as you didn’t literally break a commandment, you were still law-abiding if you did anything just short of it. For example, you could lose your temper and beat somebody up terribly, but so long as you didn’t kill them, you wouldn’t have broken the commandment that says, “You shall not murder.”
Jesus teaches, by contrast, that the desire, intention, and attempt to commit an action are all of one piece with the action itself. The commandment against murder is actually meant to warn us away from hatred, bitterness, and assault, not just actual murder. Jesus taught an inward righteousness whose goal was to be “perfect . . . as your heavenly Father is perfect,” in thought, word, and deed.
The first two examples that Jesus chooses to illustrate this teaching come from the Ten Commandments: “You shall not murder” and “you shall not commit adultery.” The Ten Commandments themselves were not meant to be interpreted legalistically. That is, their meaning was not supposed to be limited to a strict literal reading, as if they were forbidding only the specific named practices. Rather, they were all provided as examples of the kinds of things that God does and doesn’t want us to do. We are supposed to determine from them, by inference and analogy, many other kinds of things that we should and shouldn’t do.
This principle is illustrated right within the Ten Commandments themselves, when the last one says not to covet your neighbor’s wife, or his house or land, or any of his servants, his ox or his donkey, or anything that belongs to your neighbor. In other words, specific examples are given to illustrate a principle that is meant to be applied generally. As I write in my Deuteronomy-Hebrews study guide, “The Ten Commandments are a brief but powerful moral code because they teach general principles through specific rules that can be applied to a wide range of contexts. The literal application of these rules is narrow, but they all provoke reflection on their underlying principles, and these can speak to a broad variety of situations.”
The commandment against adultery, therefore, is not meant to show just that a person who is married shouldn’t have sexual relations with someone else they’re not married to. Rather, it shows more generally that sexual relations should take place only between a husband and wife within marriage. This general application would also rule out sexual activity between two people who aren’t married. And Jesus’ teaching in the Sermon on the Mount shows that there should also not be the desire, intention, or attempt on their part to have sexual relations—even through that long, lingering look. This teaching also shows that any use of pornography is not in keeping with God’s intentions.
But how, then, would anyone get married “if there weren’t some lust involved”? I think it’s important to distinguish between sexual attraction and lust. I believe that people can experience a pure sexual attraction for another person that is actually expressing a deep admiration for everything about them—their body, yes, but also their character, personality, passions, abilities, and even the depth of their Christian commitment. Feeling this kind of attraction can be a sign that perhaps you should think and pray carefully about marrying this person.
Lust, on the other hand, is a shallow, self-indulgent desire. It wants simply to consume something of another person based on their most superficial characteristics. Someone who’s attracted to you in that way isn’t paying you much of a compliment (they hardly know you) and it’s not time to think about marrying them.
Put simply, without that sexual spark in a marriage, it’s going to be a long 50 years. But that spark is supposed to be ignited when everything about one person finds companionship, challenge, help, and mystery in everything about another person. If it’s simply a mating instinct, there’s a whole lot more both people could discover about themselves, each other, and God’s purposes for their lives by waiting before mating.
Good Question 
The Bible teaches it’s best not to marry, and when the Holy Spirit is indwelling inside and guides you, living a chaste life is really not that hard. There have been many Christians who lived chaste lives; C. S. Lewis is right when he writes, in Mere Christianity, that the modern world’s view of sexuality is skewed and has been perverted. Its sole purpose is for the begetting of children — see Augustine’s De bono viduitatis and De bono coniugali. Sex and marriage really are not necessary to live a meaningful life.
May Christ always be with you.
Thank you for your comment. I would actually not say that the Bible teaches it’s best not to marry. Rather, the Bible calls each person to follow the way of life that God has prepared for them, whether this means marriage or singleness. Paul concludes his discussion in 1 Corinthians about whether a person should marry by saying, “Each has his own gift from God, one of one kind and one of another.” So both singleness and marriage are gifts from God. Similarly, when the disciples said to Jesus that if divorce were only permissible under very limited circumstances, “If such is the case, it is better not to marry,” Jesus replied, “Not everyone can receive this saying, but only those to whom it is given.” I take this to mean that such a committed marriage would have to be granted and sustained by God. But that’s how it’s supposed to be anyway. Jesus went on to speak about people who chose not to marry for the sake of the kingdom of God, that is, so that they could serve God more freely and flexibly with the advantages of singleness. This is actually what Paul is commending in 1 Corinthians. As for the purpose of sexuality, I would say that it goes beyond procreation. It’s meant to be a joyful celebration of the intimacy between husband and wife that, in the process, strengthens their relationship. It has been compared to communion or the Lord’s Supper as something that “even as it declares what is true, makes it more true.” I think the traditional marriage service expresses it well: “The union of husband and wife in heart, body, and mind is intended by God for their mutual joy; for the help and comfort given one another in prosperity and adversity; and, when it is God’s will, for the procreation of children and their nurture in the knowledge and love of the Lord.”
God of Uganda bless you, content was so helpful